Duct Work

Balancing

Balance quality grading

Fan Balancing, Impeller Balancing, Rotor Balaning in Delhi India. The relationship of permissible eccentricity a with speed n
for a number of balance quality grades, G1 , G2.5, etc. specified in ISO 1940.
The international committee responsible for this specification has tentatively
(1973) proposed quality classifications for particular products. It will be seen that G 6.3 is the grade
considered appropriate for fan impellers.

Close tolerance on the shaft-hub fit are essential, and must not be spoiled by careless fitting. Dynamic unbalance will be produced by a small run-out such as might result from forcing the impeller on against a bruised shaft or shoulder.

Impeller with a breadth exceeding some 20% of the diameter are likly to require dynamic balancing.this involves driving the rotor in the bearings of a balancing machine which are soft mounted in the horizontal direction. The resulting bearing vibration are picked-up, analysed and displayed to show the positon and value of the counterweight to be attached in two selected correcting planes.